Dies for double-twist augers.



PATENTED FEB. 21, 1905.

I. W. SMITH.

DIES FOR DOUBLE TWIST AUGERS.

APPLICATION FILED APR. 25, 1904.

Massey.-

ter of the auger to be forged therein.

UNITED STATES Patented February 21, 1905.

PATENT OEEicE.

DIES FOR DOUBLE-TWIST AUGERS- SPECIFICATION forming part of Letters Patent No. 783,147, dated February 21, 1905.

Application filed pril 25, 1904- Serial No. 204,787.

To all 11/71/0717, it 771,007 concern:

Be it known that I, IVAN W. SMITH, a citi- Zen of the United States of America, residing at Holyoke, in the county of Hampden and State of Massachusetts, have in vented new and useful Improvements in Forging-Dies for Double-Twist Augers, of which the following is a specification.

This invention relates to the manufacture of augers, and especially to dies therefor, the object of the invention being particularly to provide an improved die whereby a doubletwist auger may be forged from a bar of steel in an ordinary trip-hammer and finished to such a degree of perfection as to require only the polishing operation to finish it, (as far as the body of the anger is concerned,) the straightening and the truing operations being dispensed with; and the invention consists in the construction set forth in the following specification and pointed out in the claim.

In the drawings accompanying this specification the invention is clearly illustrated.

In the drawings, Figure 1 is a plan view of the face of each die, both dies being included in this one figure. Fig. 2 is an end view of one of thedies; and Fig. 3 is a vertical section of two dies in operative relation one to another constructed according to this invention, a partially-finished auger, shown partly in section, being located between the dies.

Referring to the drawings, a andb indicate upper and lower dies, respectively, and each die has formed centrally and longitudinally thereof a semicircular groove 0, the diameter of which is substantially equal to the diame- In the groove 0 of each of the dies are three diagonally-disposed bars or ribs lettered (.Z, c, and f in the die a and (l, c, and f in the die 1), those in the last-named die being located in the groove 0 at the same angle relative to the axis of said groove as those in the die a, but inclined in the opposite direction, to the end that when the dies are in the position shown in Fig. 1 the ribs in each die will lie across those in the other, and the longitudinal centers of the ribs in each die will intersect each other substantially at the axis of the grooves c. In cross-section each rib is substantially semicircular, as shown in Fig 1, and each end of each rib is flush with the face of the die for a certain distance from each end thereof extending toward the center of the rib. At the center of each riba groove h is formed which is parallel in its general direction with the axis of the groove 0, each end. of the groove it, however, being made flaring from the center of the rib outward, to the end that in the forging of an anger the diameter of the central stem or axis thereof will be equal to double the radius of one of the grooves h.

In forging single-twist angers they are made as described in United. States Letters Patent issued to me on October 6, 1903, numbered 740,936. Obviously it would be impossible to forge a double-twist auger in any such dies. Furthermore, it is a fact that it is impossible to forge a true spiral between dies having only two ribs instead of three, as shown herein. The reason for this will appear from the description of the operation of the dies forming the subject of this application, which follows: In forging an auger with the dies shown and described herein the bar j, suitably heated, is introduced between the dies, with the extremity j thereof (from which the gimlet-point is subsequently formed) extending a short distance beyond the ribs f and f, the ribs dd being toward the operator. The hammer is then started, and by slowly rotating the bar the convolutions m are formed therein. The diameter of the bar is such that when the axis of the auger has been reduced to the diameter shown in Fig. l the metal between two convolutions will be just sufficient to fill the space 0 between the ribs. As soon, therefore, as the convolutions begin to form after the bar has been introduced between the dies the ribsfandf become practically guiding-ribs, and by the time one complete convolution has been formed, or nearly so, the bar 1' may be rotated as fast as the hammer will form the stock into the proper shape between the ribs 0 e and d d. the latter serving to break down the stock and the greater part of the work being performed by the ribs 0 and e. The ribs f and f, besides serving as guiding-ribs, serve also as finishing-ribs, and when the auger issues from the farther end of the dies it is straight, and the convolutions are all uniformly spaced and the outside diameter and axial diameters are both true and finished down to size. From the fact that two full convolutions are constantly inclosed between the dies there is no chance for the metal to shoot,

I as it must if the ribs fand f were omitted; but

with these ribs the auger is so near completion when it reaches themthat but little of the metal is displaced by the action of these ribs. The latter, therefore, at the same time serve to back up the convolutions being formed between the ribs 0 a, and these serve to back up the convolutions being formed between the ribs d and d, all of which cond uces to the formation of the convolutions in equallyspaced relation one to the other, and so much of the auger being always located between the dies it is practically impossible to forge an auger between them which will not be straight axially.

I am aware that dies have heretofore been made for truing or twisting double-twist angers; but much of the strength of the material is lost in making augers in this way as compared with the forged auger and, fur thermore, it requires a preceding forging operation, whereby the stock from which the convolutions of the auger are made is first flattened. Furthermore, as is well known, augers thus made must be trued afterward and straightened, which not infrequently results in an undue cutting away at the axis of the tool. I am aware, also, that dies have been made whereby the entire auger has been formed by pressure in a hydraulic press at one operation. This, however, is an operation distinct from forging, and the dies used are not in any sense forging-dies and cannot be used as such, and it is a more expensive method in that it leaves a fin or flashing to be cut or ground off, and to be successfully operated it requires that the metal should be heated to a higher degree of temperature than is prudent.

From the foregoing description it is obvious that a double-twist auger could not be forged between dies having only two ribs, for the reason that it requires at least two ribs constantly at work to complete a convolution in the auger, and if only two ribs were present that part of the convolution issuing from between the second set of ribs would be broken down by the action of the latter and the metal crowded forward in the direction of movement of the auger through the dies, but with the third rib forward of these two to hold the stock in place and to serve as guides in the manner described angers may be quickly forged which will be true, straight, and ready for the polishing operation after the point j has been tapered to receive the usual screwthread. Preferably this point is tapered by introducing it into the depressions q q,formed in the edge of the dies at and 6, whereby the point is drawn down to a taper, as shown in Fig. 1 in dotted lines and lettered 7.

Having thus described my invention, what I claim, and desire to secure by Letters Patentof the United States, is r A pair of forging-dies for double-twist augers, each consisting of a block having a semicircular groove extending longitudinally of one side thereof; three ribs substantially semicylindrical in cross-section diagonally disposed in vsaid groove and oppositely inclined in the two dies, the edge ofthe ribs lying in the same plane as the face of the die, there being a groove across the face of each rib, the axis of which substantially coincides with the axis of the groove in said block.

IVAN W. SMITH.

Witnesses:

WM. H. OHAPIN, K. I. CLEMo-ns. 

